Interesting thought, TB.
I'm actually currently working on a project going in the other direction: starting with a 1/720 Academy Titanic---the hull lines of which are eerily close to the Royal Navy WW1 seaplane carrier HMS Ben-my-Chree (one of whose aircraft launched the first successful sinking of an enemy vessel by an airborne torpedo in 1915). That actual ship was itself converted from a pre-war Isle-of-Man packet steamer, so her resemblance to a liner is neither coincidental nor surprising; what did surprise me is that the Chree was designed and launched in 1908...about the time the White Star Line's infamous Olympic class were being ordered and designed.
Hull lines are virtually spot-on, though the scale is different---the Chree will turn out about 1/320 or so. Almost all hull detail is wrong or incorrectly scaled, so filler is my friend:
Lots of scratch-building to do from 'deck-up'---including tiny-scale biplane aircraft---but the pre-made hull is a very handy start for a long-dreamed-of project.
So the question is...have you ever built a liner from a warship hull?